Armellinoite-(Ce) is an extremely rare hydrous cerium arsenate mineral discovered in the Brosso mine in Italy. It typically forms small, pale yellow prismatic crystals within hydrothermal vein environments and requires professional analysis for field identification due to its rarity and similarity to other REE-arsenates.
Is this armellinoite-(ce)?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch armellinoite-(ce) with a known reference. Armellinoite-(Ce) sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Armellinoite-(Ce) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Armellinoite-(Ce) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, pale yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic crystals.
Often confused with
Armellinoite-(Ce) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Cheralite is the harder of the two (Mohs 5 vs. 3-4).
How to tell apart: Monazite-(Ce) is the harder of the two (Mohs 5-5.5 vs. 3-4); luster reads vitreous on Armellinoite-(Ce) and resinous on Monazite-(Ce).
Often found alongside armellinoite-(ce)
Minerals reported to co-occur with armellinoite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ce,REE)AsO₄·H₂O
- Mohs hardness
- 3-4
- Density
- 4.67 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphic Rocks
- Typical price
- $100-500 for micro-specimens
Where rockhounds find armellinoite-(ce)
Classic worldwide localities
- Brosso Mine, Piedmont, Italy
Field-hunting tip
Look in hydrothermal veins in metamorphic rocks country — that is the host setting where armellinoite-(ce) typically forms. If you start seeing garnet, magnetite, hematite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify armellinoite-(ce)?+
Where is armellinoite-(ce) found?+
How much is armellinoite-(ce) worth?+
Is armellinoite-(ce) safe to handle?+
What rocks look like armellinoite-(ce)?+
What minerals are found with armellinoite-(ce)?+
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Find armellinoite-(ce) on the map
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